Contrary to expectations, highly connected plant populations can experience less impact from infectious disease than isolated plant networks. What happens to pathogens in natural populations has been poorly studied, because they rarely cause devastating disease outbreaks. Thanks to a long-term study of an inconspicuous fungal-plant disease system, we have now gained some surprising insights.
During the 12-year study, it was discovered that clustered and linked host-plant patches showed lower levels of fungal damage and higher fungal extinction rates than more distant patches. This phenomenon is explained by high gene flow and rapid evolution of host resistance within the connected patches. In most years, only a small fraction (less than 10%) of plant populations of Plantago lanceolata on the Åland Islands in the Baltic were infected by the Podosphaera mildew fungus in any given year, but infection turnover was high (likely due to high overwinter mortality of the pathogen). These findings have broad implications for ecology, disease biology, conservation, and agriculture.
Link to the paper in Science:
http://www.sciencemag.org/content/344/6189/1289.abstract
A perspective by Meghan Duffy in the same issue:
http://www.sciencemag.org/content/344/6189/1229.summary
